In the present invention the use of metallization to create infrared reflecting barriers is adopted for clothing or outdoor equipment such as sleeping bags or tents. These radiant barriers, require careful insulation from heat loss via conduction.
Corrosion, particularly in salty environments, of these metal layers through oxidisation can be considerable and methods known in the art are adopted to help prevent oxidisation.
When a moisture vapor permeable substrate is coated over substantially an entire surface using conventional methods such as air knife coating, flexographic printing, gravure coating, etc., the coating reduces the moisture vapor permeability of the substrate. If the starting substrate has an open structure and is highly air permeable, the substrate can retain sufficient moisture vapor permeability after coating to be useful in certain end uses, such as apparel. For example, fabrics described in U.S. Pat. No. 5,955,175 to Culler are both air permeable and moisture vapor permeable after being metalized and coated with an oleophobic coating.
When the starting moisture vapor permeable substrate is a non-porous monolithic membrane, conventional coatings result in significant covering of the surface of the substrate. This results in a coated substrate having significantly lower moisture vapor permeability than the starting substrate. This is undesirable in apparel or outdoor equipment products, which are desirably permeable to moisture vapor while at the same time forming a barrier to infiltration by air and water. As described by Sympatex in U.S. Pat. No. 6,800,573 it is possible to coat these non-porous vapour permeable substrates using a plasma treated vapour deposition metalization process and maintain good vapour permeability.
US Patent Application Publication US 2004/0213918 A1 (Mikhael et al.) discloses a process for functionalizing a porous substrate, such as a nonwoven fabric or paper, with a layer of polymer, and optionally a layer of metal or ceramic. According to one embodiment, the process includes the steps of flash evaporating a monomer having a desired functionality in a vacuum chamber to produce a vapor, condensing the vapor on the porous substrate to produce a film of the monomer on the porous substrate, curing the film to produce a functionalized polymeric layer on the porous substrate, vacuum depositing an inorganic layer over the polymer layer, and flash evaporating and condensing a second film of monomer on the inorganic layer and curing the second film to produce a second polymeric layer on the inorganic layer. Mikhael et al. also discloses another embodiment including the steps of flash evaporating and condensing a first film of monomer on the porous substrate to produce a first film of the monomer on the porous substrate, curing the film to produce a functionalized polymeric layer on the porous substrate, vacuum depositing a metal layer over the polymer layer, and flash evaporating and condensing a second film of monomer on the metal layer and curing the second film to produce a second polymeric layer on the metal layer.
US Patent Applications US 2007/0166528 A1 (Barnes et al.) discloses a process for oxidising the surface of a metal coating with an oxygen-containing plasma to form a synthetic metal oxide coating, making a superior resistance to corrosion of the metallized porous sheet.
Methods for both improving the moisture vapour permeability of the composite and insulating the metal layer from conduction are disclosed in the present invention.